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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 4/5
Edited by: B.H.V. Topping
Paper XI.3

Computer-Aided Design of Pile-Raft Foundations

M. Sobaih* and A. Al-Khatib+

*Structural Engineering Department, Cairo University, Egypt
+Consulting Engineer, Jeddah, Saudi Arabia

Full Bibliographic Reference for this paper
M. Sobaih, A. Al-Khatib, "Computer-Aided Design of Pile-Raft Foundations", in B.H.V. Topping, (Editor), "Proceedings of the Third International Conference on Civil and Structural Engineering Computing", Civil-Comp Press, Edinburgh, UK, pp 321-329, 1987. doi:10.4203/ccp.4.11.3
This paper deals with the computer-aided design of raft foundations supported on piles. This type of foundations is usually encountered when heavy loads imposed by immense structures (e.g., high-rise buildings, nuclear power plants, etc.) are supported on a weak soil.

The proposed approach is based on dividing the problem into two parts. The first is the analysis process while the second is the design process. For the analysis the simple and yet efficient method of representing the soil and piles by Winkler springs is used together with the finite difference idealization. Separation of the raft from the underlying soil is taken into account. Hence, raft deflections, the underlying pressure and the internal forces are obtained. For the design part a decision design method is proposed which comprises many advantages, e.g., interactive facility, simple input/output, different alternatives for design and the latest ACI code provisions. The whole process has resulted into a computer package called CADPRF (Computer-Aided Design of Pile-Raft Foundations) that can be run on an IBM personal computer or its compatibles.

The proposed CADPRF program has been used to solve thirty-two typical cases in order to study the effect of different parameters on the behavior of such foundation system. These parameters include the type of soil, number of piles, length-to-diameter ratio for piles and the type of piles. Comparison with the classic simple method is done. Many useful conclusions have been drawn and presented.

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